In my application i am having 4 places with its longitude and altitude(Given).Now i want to find the nearest place from user.
So anyone can tell me the solution for it or provide me some source code or demo for this.
Thanks to all
Create an CLLocation of the points:
CLLocation* locationx = [[CLLocation alloc] initWithLatitude:lat longitude:lon];
And the compare the points with:
double distance = [userposition distanceFromLocation:locationx];
Keep the nearest location.
Edit:
If you really mean "longitude and altitude" then I dont know how.
just took 10 seconds to ask google and find this, wich describes how to calculate the distance beween two points given latitude and logitude:
http://www.movable-type.co.uk/scripts/latlong.html
all you have to do is calculate the distance to all 4 points and choose the lowest one.
ETDI: i'm sure you're also given the latitude, otherwise you won't even have specific coordinates. if this wasn't a type and you really have to take the altitude into account, take a look at this question at google answers
picknick describes a native class method.
This is probably going to use the Haversine formula (search the web or stackoverflow for discussions) to measure distances.
In my experience, writing your own Haversine is usually faster than using a system/app-provided one, although this is on Windows where COM overhead can be "problematic" as it were!
The Haversine (and many similar geometry-on-the-Earth) formulae can be found here:
http://williams.best.vwh.net/avform.htm
(this is one of my few bookmarks I go back to for reference on a regular basis!)
for example user is at x=0,y=0
Calculate the distance by doing : SquareRoot(x2^2 & y2^2)
You will get a distance. Look through all points and compare which distance is the shortest
Related
May I know how I should calculate the bearing of one point relative to another? All the formulas I'm seeing on the Internet are for lat/lon coordinates. I'm working with the Cartesian coordinate system here and am unable to find a solution. Please help!
Use atan2 function (IIRC your objective-c should have it).
It gives you a result between -PI and PI. You have to map it to 0-360 if you need it.
Not really an answer to your question, but if you're getting your points using CLLocationManager, each CLLocation has a course property, which gives you the bearing of your journey for the given point. For the actual math, see Axeman's answer.
I have around 800 geo co-ordinates in my iPhone app as a flat file. I am searching for an effective way to find an algorithm which will take the current user location, loop through all these 800 coordinates and pull only the coordinates which are in 10 miles vicinity. How effectively this can be done? Also please share links which will get me the basic understanding on the maths behind this.
Here is a link for a question where the final code of OP may help you understand the how to create locations from coordinates and how to compute the distance between them.
Here is how to create a location:
CLLocation *location = [[CLLocation alloc] initWithLatitude:latitude longitude:longitude];
And here is how to find the distance between two locations:
CLLocationDistance distance = [locationA distanceFromLocation:locationB]; //CLLocationDistance is a double
However you don't have to sort the locations. Just loop through them and add the near locations to an array.
First, I think everyone agrees that to compute distance, you need to use the Haversine function.
Finding the closest point to a given point
If the search time is an issue (iterating over the 800 data points you mentioned) then how about a 2D hash? Simply load the dataset into buckets or regions based on lat/long - then, you won't have to search through the whole data set - only the possible buckets that may contain matches.
Good hash function for a 2d index
I've developed an iPhone application to parse data from an XML file. This data contains a set of longitudes and latitudes for different places.
How do I detect nearest of them according to my current location on the map and how do I set set a range to show places in this range?
CLLocation *myLocation = [[CLLocation alloc] initWithLatitude:myLatitude longitude:myLongitude];
CLLocation *myXmlLocation = [[CLLocation alloc] initWithLatitude:xmlLatitude longitude:xmlLongitude];
CLLocationDistance distance = [myLocation distanceFromLocation: myXmlLocation];
This is in meters, so you must do any converting from there. They are also linear, so these aren't driving direction lengths by any means. Good luck.
some trig, but really not too difficult.
this page has an example script, not in your language, but it contains explainations and the equations you need.
http://www.movable-type.co.uk/scripts/latlong.html
and also, please don't write run-on sentences, it took me a while to read your question.
#Vinnie said is absolutely right but these values is air distance.
Also this method is deprecated in iOS 3.2
- (CLLocationDistance)getDistanceFrom:(const CLLocation *)location Parameters
You can't find the distance based on roads with the Apple SDK. Try to use google APIs for finding distance between two points on earth on roads.
I have create a program to find out my current location using IOS corelocation framework.It works fine.
I need to create a program that list nearest branchaes of a shop chain, while a user travel with the phone.My data base contains the branches details with Latitude and lognitude.How i compare with these details to find out the nearest branch.
Help is highly appreciated.Anybody knows any example program
Thanks,
VKS
You can make use of distanceFromLocation: method of CLLocation.
distanceFromLocation:
Returns the distance (in meters) from the receiver’s location to the
specified location.
(CLLocationDistance)distanceFromLocation:(const CLLocation
*)location
Parameters
location
The other location.
Return Value
The distance (in meters) between the two locations.
Discussion
This method measures the distance between the two locations by tracing
a line between them that follows the curvature of the Earth. The
resulting arc is a smooth curve and does not take into account
specific altitude changes between the two locations.
Availability
Available in iOS 3.2 and later.
By using this method to get the distances of the shops with your current location, you can then sort the list based on the distance to get the nearest branch
VKS, I got to solve the exact same problem too now (using apptarget iOS 5). Do you have any example code / snippets / tips to share for this problem, that I assumed you solved a long time ago? The above is very good explanation from 7KV7, but some examples will speed up my process a lot. Thank's :-)
I'm trying to calculate the distance between two places user Core Location. I've found a few posts that state to use
-(CLLocationDistance)distanceFromLocation:(const CLLocation *)location
Found some other test code in the thread below:
CLLocationDistance NaN
I'm not sure how to put it all together, to get the result I want ?
Anyone any thoughts ?
Regards,
Stephen
If you have a location named myLocation and want to find the distance from another location, say, restaurantLocation, then it seems you would do something like
CLLocationDistance distance = [myLocation distanceFromLocation:restaurantLocation]
This will give you the distance, in meters, between the two.